160 J. D. Robertson — Zinc Sulphide from Kansas. 



The following analyses of unaltered ores of both types, after 

 calcination, are selected from the company's tile of numerous 

 commercial analyses : I, spathic siderite from No. 2 mine, by 

 Mr. A. S. Bertolet, of Crown Point ; II, iron-stone from Mt. 

 Thomas, both from different parts of the second basin : 



i. ii. 



Ferrous oxide 2-78 



Ferric oxide 68*23 65-73 



Magnesia 707 5-72 



Alumina 2-27 3'01 



Lime.... 3-36 4-35 



Phosphoric acid 0'06 0-3188 



Silica 11-65 17-18 



Manganous oxide .. 2 - 92 2*66 



Sulphur 0-62 0-78 



* 99-96 99-75 



Metallic iron 49-92 46.70 



The low proportion of alumina in contrast with the large 

 proportion of magnesia will not fail to be noticed. This is 

 remarkable throughout the whole series of analyses. The 

 detrital derivation of the earthy admixtures from basic — nota- 

 bly hornblendic rocks as prevailing in the Archaean highlands — 

 need scarcely be pointed out in explanation of this peculiarity 

 of these unaltered paleozoic iron-stones. 



Washington, 26th April, 1890. 



Akt. XIX. — On a netv variety of Zinc Sulphide from Chero- 

 kee County, Kansas ; by James D. Robektsok 



A NEW and peculiar sulphide of zinc was found in south- 

 eastern Kansas a short time since, remarkable from the fact 

 that it is nearly pure white and completely amorphous. 



This singular mineral is found on the Moll Tract in the 

 center of the town of Galena, Cherokee County, Kansas. The 

 ore body, which is reached by a shaft about 90 feet in depth, 

 consists of zinc blende with some large crystals of galena dis- 

 tributed through it. It is about 25 feet wide, 20 feet high, 

 and 100 feet long, so far as explored. The blende has under- 

 gone much decomposition from the action of surface waters, 

 the sulphide oxidizing to sulphate and being completely re- 

 moved in solution. Thus no calamine or smithsonite are 

 formed and the siliceous gangue rock remains, a cellular mass, 

 showing casts of the dissolved blende crystals. In the center 

 of the ore body and surrounded on all sides by partially 

 decomposed ore, is a flat opening three to four feet wide, six 



